It is demanded for a lithium ion secondary battery mounted on a moving object such as a vehicle to show stable performance over a long period. However, in the lithium ion secondary battery, a battery capacity may be degraded and a life of the battery may be decreased according to a use method or a storage method thereof.
The invention to suppress the degradation of the battery capacity by storing a manganese-type lithium ion secondary battery using lithium manganate in a positive electrode material in a specific state of charge (SOC) is disclosed in PTL 1.